Elevator safety-brake



(No Model.)

W. E. NIOKERSON.

ELEVATOR SAFETY BRAKE.

No. 403,438. Patented May 14, 1889.

FT .5. V\/ITI\IE 555 s drmm UNITED STATES PATENT OFFICE...

IVILLIAM E. NICKERSON, OF CAMBRIDGE, MASSACHUSETTS.

ELEVATOR SAFETY-BRAKE.

SPECIFICATION forming part of Letters Patent No. 403,438, dated May 14, 1889. Application filed February 14, 1889. Serial No. 299,820. (No model.)

lowing the elevator-carriage to descend when from any accident or other cause the belts and brakes are simultaneously inoperative. This object I attain by the mechanism shown in the accompanying drawings, in which Figure 1 is an elevation showing the hoisting mechanism of an ordinary belt elevator, parts being represented as broken out to show other parts more clearly. Fig. 2 is a perspective view showing the parts that more directly relate to myinvention, and Fig. 3 shows in detail one feature of my invention.

In the drawings, Fig. 1, I have represented the winding-drum by B and its shaft by B. This drum is driven by the usual worm-gear, B shaft B and fixed pulley B", the pulleys C and 0 being loose and provided with the ordinarybelt-guides, L and L and con trolling devices L L L and L L L, operated by cams attached to the hand-rope pulley E, the hand-rope being represented by E E and the hoisting-rope by R.

D represents a brake-wheel made in the usual manner, having a friction-strap, D, and

weight D and is connected by suitable mech anism (not shown) to the hand-rope pulley E, by which it is held inoperative while the drum is being rotated by the belts.

As all of the above-named parts are to be found in common use in connection with elevators, I will not describe them particularly.

I will now describe that part of the device that illustrates one form of application of my invention.

Upon the worm-shaft B I place an auxiliary brake-wheel, K Figs. 1 and 2. This brakewheel K has a friction-strap, K and a weightlever, K, and weight K. The lever K swings on a pivot, 7o, Fig. 2, and is connected at 7t" and 7t" to the strap K in the usual manner, so that if the weight K and the lever K are left free to act the strap K will be brought to bear with great frictional strain upon the brake-wheel K, and, acting through the wormshaft B check or stop the motion of the elevator winding-drum B. To prevent this action of the auxiliary brake,I have a holdingpost, J, pivoted to the lever K at J, Fig. 2, the end of which rests upon the floor, as shown. This device of a holding-post, J, is used simply as a convenient and simple illustration of a method of effecting the desired result, it being well understood that a great variety of tripping or let-off devices are in use for such purposes and can be readily applied as a part of my mechanism.

The device that I have selected for actuating my let-off post consists of a wheel, M, attached to the shaft B and provided with sliding radial arms M M each of which has a weight, M. These arms and their weights are held in place by a spring, S, as shown in Figs. 2 and 3, so that their ends project but a short distance beyond the periphery of the wheel M. The springs S are of such tension that they are able to hold the radial arms M back toward the center of the wheel M when the wheel is not in motion or is rotating at or below its normal velocity; but if the rotation exceeds a safe velocity then the arms M acting by centrifugal energy, will overcome the force of the springs S and move radially outward, so as to come in contact with the stud H on the sliding bar H, Fig. 2. This action will throw the sliding bar back and cause the lever H pivoted at h, to throw the lower end of the post J outward, and thus allow the lever K to fall and set the friction-strap K in position to retard the brake-wheel K, and thus stop or check thevelocity of the elevator machinery. The radial arms M in acting upon the sliding bar H indirectly, are also used to cause the shipping-levers L and L, as well as the primary brake deviceD D ,to act. To attain this result, it is not essential to my invention to use any particular form of transmitting device; but I will now describe one form that may be used.

F, Fig. 1,1's a rope or chain that is attached to the hand-rope pulley E, so that when the drum is unwinding any strain exerted upon it will cause the hand-rope pulley E to rotate sufficiently to throw the lowering-belt shipper from the fast pulley B to its loose pulley, and in doing this will also cause the primary friction-strap D on the brake-wheel D to act. The rope F passes over the sheave F to the weight IV. The weight IV is suspended by the rope W, which passes over the sheave W Fig. 1, to the end of the'lever W Fig. 2, the lever WV being pivoted at W and is held in its normal position by the upturned end H of the sliding bar H when said bar is in its normal position, as shown in Fig. 2; but if the sliding bar H is forced back by the action of one of the arms M (as has been set forth) then the part H will pass out from under the lever WV and allow the rope W to slip off and throw the weight W onto the rope F, and, acting through it, cause the hand-rope wheel E and its connected cams to put the brake device D D if intact, into working action in conjunction with the auxiliary brake.

In Fig. 1 the belt-shipping mechanism is shown in the position that it occupies when both belts are on the loose pulleys that is, when the elevator-carriage is at rest. In this case the rope F is loose, as shown, the small weight w being attached to it for the purpose of keeping it slightly taut on the pulley E.

My device comes into action when from any cause the safety-wheel M is made to rotate with a velocity that it would have when the elevator-carriage is moving downward too rapidly. This can happen when either of the belts is broken or run off from the pulleys, and also when the regular brake D D is out of order or insufficient to hold the load on the does not work sufliciently well, or is not set) shall at once throw the belt-shipper to the position of rest, set the primary brake, and also the auxiliary brake, so that the winding-drum will cease to revolve and the elevator-carriage will be checked or stopped in its descent, the invention being, in fact, the combination of one or more brakes with a centrifugal letoff device and a transmitting mechanism adapted to set the brakes when the speed of the elevator-carriage in descending exceeds the limit of safety.

I claim- 1. In an elevator hoisting device, the combination of the hand-rope wheel E, the rope F, and weightW with the rope W, lever W sliding rod H, having a stud, H, and the wheel M, having the slidable arms M substantially as and for the purpose set forth.

2. In an elevator hoisting device, the combination of the shaft B brake K K leverK',

and post J with the lever H sliding rod H,

having a stud, H, and the wheel M, having slidable arms M all operating substantially as and for the purpose set forth.

WILLIAM E. NIGKERSON. \Vitnesses:

FRANK G. PARKER, MATTHEW M. BLUNT. 

